Helium recovery refers to the collection of helium from the process of use for reuse. There are various methods for helium recovery, purification, and liquefaction, among which the common ones are achieved through cooling and compression. When helium is cooled to a temperature below its boiling point, it will become a liquid. Therefore, by exposing helium to a low-temperature environment, it can be liquefied. Common cooling methods include using liquid nitrogen or a refrigerator.
During the liquefaction process, helium is first collected into a sealed container. Then, by placing the container in a low-temperature environment, the helium gas gradually cools and converts into a liquid. During this process, attention needs to be paid to controlling temperature and pressure to ensure that helium can be liquefied smoothly. Once helium is liquefied, it can be stored and transported for subsequent use.
However, liquefaction is only the first step in helium recovery. In order to improve the purity of helium, a purification process is also required. The purification of helium usually involves removing impurities and other gases. Common purification methods include molecular sieve adsorption, membrane separation, and coagulation separation.
Molecular sieve adsorption is a commonly used method for helium purification. It utilizes the special structure and adsorption performance of molecular sieve materials to adsorb impurities and other gases from helium. By adjusting the selection of adsorbents and operating conditions, efficient purification of helium can be achieved.
Membrane separation is another common method for helium purification. It utilizes special membrane materials to selectively penetrate and block different gas molecules, separating impurities and other gases from helium. Membrane separation has been widely used in helium purification due to its advantages of simple operation and low energy consumption.
Solidification separation is a purification method based on the differences in solidification points of substances. By controlling temperature and pressure, impurities and other gases in helium are solidified and then separated. This method is suitable for situations where helium contains high boiling point impurities.
In summary, the liquefaction process of helium recovery and purification involves converting helium into liquid through cooling and compression, and removing impurities and other gases through methods such as molecular sieve adsorption, membrane separation, and solidification separation. These processes require precise control and operation to ensure efficient recovery and purification of helium. By recycling and purifying helium, we can better utilize limited resources and provide high-quality helium for applications in various fields.